Facts. We have never even seen him go all out. We don’t even know his bounty yet (he clearly must have one if the Marines are hunting him). He was introduced so early and has remained at the top of the verse. People are insane if they do not realize that his power is about to be ridiculous compared to what we’ve from other sword users.
Yeah, at this point 1 Billion+ bounties are the norm - heck even Zoro and Sanji are probably crossing that. Which probably means that expecting a 2-3 Billion bounty for Mihawk to hype the moment where we get the Warlord's adjusted bounties is rational since it'd be weird if his bounty is comparable to Zoro's. And even that is actually insane given his lack of threat to WG and how he is a lone wolf type character. And also reflects on his powerlevel since thats what its gonna be based on primarily.
Regarding the sword feats, we have already seen insane cutting feats from Zoro - the Pica cut, Rooftop Hiryu Kaen cutting the other side of Onigashima Island as collateral showcasing an Island wide range, Perma Scarring Kaidou with Ashura etc,. If Oda wants to top that, then Mihawk is legitimately gonna look insane!
The people who compared him to Vista all this while are gonna look like actual clowns.